package com.shenjianquan.cryptography.handel;

public class DESEncrypt {
    
    

    /**
     * @author generalandroid
     *
     * 根据DES算法原理实现DES加密算法，主要是为了更加深入地理解DES算法
     * **/
        //初始置换
        private int[] IP={58,50,42,34,26,18,10,2,
                60,52,44,36,28,20,12,4,
                62,54,46,38,30,22,14,6,
                64,56,48,40,32,24,16,8,
                57,49,41,33,25,17,9,1,
                59,51,43,35,27,19,11,3,
                61,53,45,37,29,21,13,5,
                63,55,47,39,31,23,15,7};
        //逆初始置换
        private int[] IP_1={40,8,48,16,56,24,64,32,
                39,7,47,15,55,23,63,31,
                38,6,46,14,54,22,62,30,
                37,5,45,13,53,21,61,29,
                36,4,44,12,52,20,60,28,
                35,3,43,11,51,19,59,27,
                34,2,42,10,50,18,58,26,
                33,1,41,9,49,17,57,25};//手残，数组数据没写全
        //E扩展
        private int[] E={32,1,2,3,4,5,
                4,5,6,7,8,9,
                8,9,10,11,12,13,
                12,13,14,15,16,17,
                16,17,18,19,20,21,
                20,21,22,23,24,25,
                24,25,26,27,28,29,
                28,29,30,31,32,1};
        //P置换
        private int[] P={16,7,20,21,29,12,28,17,
                1,15,23,26,5,18,31,10,
                2,8,24,14,32,27,3,9,
                19,13,30,6,22,11,4,25};
        private static final int[][][] S_Box = {
                {
                        { 14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7 },
                        { 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8 },
                        { 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0 },
                        { 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13 } },
                {
                        { 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10 },
                        { 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5 },
                        { 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15 },
                        { 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 } },
                {
                        { 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8 },
                        { 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1 },
                        { 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7 },
                        { 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 } },
                {
                        { 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15 },
                        { 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9 },
                        { 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4 },
                        { 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14 } },
                {
                        { 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9 },
                        { 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6 },
                        { 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14 },
                        { 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3 } },
                {
                        { 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11 },
                        { 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8 },
                        { 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6 },
                        { 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 } },
                {
                        { 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1 },
                        { 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6 },
                        { 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2 },
                        { 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12 } },
                {
                        { 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7 },
                        { 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2 },
                        { 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8 },
                        { 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11 } }
        };
        //PC-1
        private int[] PC1={57,49,41,33,25,17,9,
                1,58,50,42,34,26,18,
                10,2,59,51,43,35,27,
                19,11,3,60,52,44,36,
                63,55,47,39,31,23,15,
                7,62,54,46,38,30,22,
                14,6,61,53,45,37,29,
                21,13,5,28,20,12,4};
        //PC-2
        private int[] PC2={14,17,11,24,1,5,3,28,
                15,6,21,10,23,19,12,4,
                26,8,16,7,27,20,13,2,
                41,52,31,37,47,55,30,40,
                51,45,33,48,44,49,39,56,
                34,53,46,42,50,36,29,32};
        //Schedule of Left Shifts
        private int[] LFT={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
        /**加密轮数**/
        private static final int LOOP_NUM=16;
        private String [] keys=new String[LOOP_NUM];
        private String [] pContent;
        private String [] cContent;
        private int origin_length;
        /**16个子密钥**/
        private int[][] sub_key=new int[16][48];
        private String content;
        private int p_origin_length;
        public DESEncrypt(String key,String content){

            this.content=content;
            p_origin_length=content.getBytes().length;
            generateKeys(key);

        }

        /***代码运行结果：
         *
         原文：
         Android将军->GeneralAndroid->主博客地址：https://blog.csdn.net/android_jiangjun
         密文：
         ��Lm����=��� 4�zf4�����zj���}���~Dͪn�B��t���Du��U*e�VxC�̃Ynh\@NH ˙P�Ka�1y~4
         明文：
         Android将军->GeneralAndroid->主博客地址：https://blog.csdn.net/android_jiangjun
         *
         * **/


        /****拆分分组****/
        public byte[] deal(byte[] p ,int flag){
            origin_length=p.length;
            int g_num;
            int r_num;
            g_num=origin_length/8;
            r_num=8-(origin_length-g_num*8);//8不填充
            byte[] p_padding;
            /****填充********/
            if (r_num<8){
                p_padding=new byte[origin_length+r_num];
                System.arraycopy(p,0,p_padding,0,origin_length);
                for(int i=0;i<r_num;i++){
                    p_padding[origin_length+i]=(byte)r_num;
                }

            }else{
                p_padding=p;
            }
            g_num=p_padding.length/8;
            byte[] f_p=new byte[8];
            byte[] result_data=new byte[p_padding.length];
            for(int i=0;i<g_num;i++){
                System.arraycopy(p_padding,i*8,f_p,0,8);
                System.arraycopy(descryUnit(f_p,sub_key,flag),0,result_data,i*8,8);
            }
            if (flag==0){//解密
                byte[] p_result_data=new byte[p_origin_length];
                System.arraycopy(result_data,0,p_result_data,0,p_origin_length);
                return  p_result_data;
            }
            return result_data;

        }
        /**加密**/
        public byte[] descryUnit(byte[] p,int k[][],int flag){
            int[] p_bit=new int[64];
            StringBuilder stringBuilder=new StringBuilder();
            for(int i=0;i<8;i++){
                String p_b=Integer.toBinaryString(p[i]&0xff);
                while (p_b.length()%8!=0){
                    p_b="0"+p_b;
                }
                stringBuilder.append(p_b);
            }
            String p_str=stringBuilder.toString();
            for(int i=0;i<64;i++){
                int p_t=Integer.valueOf(p_str.charAt(i));
                if(p_t==48){
                    p_t=0;
                }else if(p_t==49){
                    p_t=1;
                }else{
                    System.out.println("To bit error!");
                }
                p_bit[i]=p_t;
            }
            /***IP置换***/
            int [] p_IP=new int[64];
            for (int i=0;i<64;i++){
                p_IP[i]=p_bit[IP[i]-1];
            }
            if (flag == 1) { // 加密
                for (int i = 0; i < 16; i++) {
                    L(p_IP, i, flag, k[i]);
                }
            } else if (flag == 0) { // 解密
                for (int i = 15; i > -1; i--) {
                    L(p_IP, i, flag, k[i]);
                }
            }
            int[] c=new int[64];
            for(int i=0;i<IP_1.length;i++){
                c[i]=p_IP[IP_1[i]-1];
            }
            byte[] c_byte=new byte[8];
            for(int i=0;i<8;i++){
                c_byte[i]=(byte) ((c[8*i]<<7)+(c[8*i+1]<<6)+(c[8*i+2]<<5)+(c[8*i+3]<<4)+(c[8*i+4]<<3)+(c[8*i+5]<<2)+(c[8*i+6]<<1)+(c[8*i+7]));
            }
            return c_byte;


        }
        public void L(int[] M, int times, int flag, int[] keyarray){
            int[] L0=new int[32];
            int[] R0=new int[32];
            int[] L1=new int[32];
            int[] R1=new int[32];
            int[] f=new int[32];
            System.arraycopy(M,0,L0,0,32);
            System.arraycopy(M,32,R0,0,32);
            L1=R0;
            f=fFuction(R0,keyarray);
            for(int j=0;j<32;j++){
                R1[j]=L0[j]^f[j];
                if (((flag == 0) && (times == 0)) || ((flag == 1) && (times == 15))) {
                    M[j] = R1[j];
                    M[j + 32] = L1[j];
                }
                else {
                    M[j] = L1[j];
                    M[j + 32] = R1[j];
                }
            }

        }



        public int[] fFuction(int [] r_content,int [] key){
            int[] result=new int[32];
            int[] e_k=new int[48];
            for(int i=0;i<E.length;i++){
                e_k[i]=r_content[E[i]-1]^key[i];
            }
            /********S盒替换:由48位变32位，现分割e_k，然后再进行替换*********/
            int[][] s=new int[8][6];
            int[]s_after=new int[32];
            for(int i=0;i<8;i++){
                System.arraycopy(e_k,i*6,s[i],0,6);
                int r=(s[i][0]<<1)+ s[i][5];//横坐标
                int c=(s[i][1]<<3)+(s[i][2]<<2)+(s[i][3]<<1)+s[i][4];//纵坐标
                String str=Integer.toBinaryString(S_Box[i][r][c]);
                while (str.length()<4){
                    str="0"+str;
                }
                for(int j=0;j<4;j++){
                    int p=Integer.valueOf(str.charAt(j));
                    if(p==48){
                        p=0;
                    }else if(p==49){
                        p=1;
                    }else{
                        System.out.println("To bit error!");
                    }
                    s_after[4*i+j]=p;
                }

            }
            /******S盒替换结束*******/
            /****P盒替代****/
            for(int i=0;i<P.length;i++){
                result[i]=s_after[P[i]-1];
            }
            return result;

        }

        /**生成子密钥**/
        public void generateKeys(String key){
            while (key.length()<8){
                key=key+key;
            }
            key=key.substring(0,8);
            byte[] keys=key.getBytes();
            int[] k_bit=new int[64];
            //取位值
            for(int i=0;i<8;i++){
                String k_str=Integer.toBinaryString(keys[i]&0xff);
                if(k_str.length()<8){
                    for(int t=0;t<=8-k_str.length();t++){
                        k_str="0"+k_str;
                    }
                }
                for(int j=0;j<8;j++){
                    int p=Integer.valueOf(k_str.charAt(j));
                    if(p==48){
                        p=0;
                    }else if(p==49){
                        p=1;
                    }else{
                        System.out.println("To bit error!");
                    }
                    k_bit[i*8+j]=p;
                }
            }
            //k_bit是初始的64位长密钥，下一步开始进行替换
            /***********PC-1压缩****************/
            int [] k_new_bit=new int[56];
            for(int i=0;i<PC1.length;i++){
                k_new_bit[i]=k_bit[PC1[i]-1];
            }
            /**************************/
            int[] c0=new int[28];
            int[] d0=new int[28];
            System.arraycopy(k_new_bit,0,c0,0,28);
            System.arraycopy(k_new_bit,28,d0,0,28);
            for(int i=0;i<16;i++){
                int[] c1=new int[28];
                int[] d1=new int[28];
                if(LFT[i]==1){
                    System.arraycopy(c0,1,c1,0,27);
                    c1[27]=c0[0];
                    System.arraycopy(d0,1,d1,0,27);
                    d1[27]=d0[0];
                }else if(LFT[i]==2){
                    System.arraycopy(c0,2,c1,0,26);
                    c1[26]=c0[0];
                    c1[27]=c0[1];//这里手残之前写成c1

                    System.arraycopy(d0,2,d1,0,26);
                    d1[26]=d0[0];
                    d1[27]=d0[1];
                }else{
                    System.out.println("LFT Error!");
                }
                int[] tmp=new int[56];
                System.arraycopy(c1,0,tmp,0,28);
                System.arraycopy(d1,0,tmp,28,28);
                for (int j=0;j<PC2.length;j++){//PC2压缩置换
                    sub_key[i][j]= tmp[PC2[j]-1];
                }
                c0=c1;
                d0=d1;
            }

        }


    }

